Electric-railway system.



K. E. STUART. ELECTRIC RAILWAY SYSTEM. APPLICATION FILED MAXI-.1914.

1,240,898. t fi ptn 25,1917.

13 SHEETS-SHEET I.

A'ITORNEY K. E. STUART; ELECTRIC RAILWAY system. APPucAriuu mm Yum-1.

Patented Sept; 25, 1917.

13 SHEETSSHEET 3.

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NTOI i -ATTORNEY K. E. STUART. 5150mm RAILWAY SYSTEM.

' APPLICATION man MAYLISTM Patented Sept, 25, 1917.

13 SHEETS-SHQET 4- "-K. ."sTuAR1-.

ELECIRIC RAILWAY SYSTEM. APPLICATION HL'ED' my i914.

' Patented Sept, 25,1917.

13 SHEETS-SHEET '5 BY 55K K. E. STUART.

ELEGTBIC'RAILWAY SYSTEM. APPLICATION FILED MAY 1, 1314.

1 ,240,898. Patented Se t. 25, 1917.

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Patented Sept. 25, 1917.

44; nrrlio RN BY KuE! STUART. ELEQTRIC RA ILWAY SYSTEM. APPLICATION FILEMAY I M.

Patented Sept. 25,,1917.

i3 SHEETS-SHEET I l.

Hls ATTORNEY K. E. STUART.

ELECTRIC RAILWAY SYSTEM. APPLICATION FILED MAY nan.-

1,240,893; I V PatenqedSept 25, 1917.

13 SHEETS-SHEET l2.

# 2 ATTORNE;

KnivnETH n. STUART, or LONDONQENGLAND,

unaware-RAILWAY srsrnm;

Original application -fi1ed April 29, 1912, Serial No. 693,973. Dividedand this 1914. Serial-No. 835,778.

To all whom it may concern:

Be it-known that I, a citizen of the United States, residing in the cityof London, England, have invented new and useful Improvements inElectrlc- Railway Systems, .of, which the following is a specification.

My. invention relates to an electric rallwaysystem suitable for thedespatch of mail,

preaching car or train is a station 1 11 question or system to I tionsexcepting that parcels, etc., in which the moving cars or trains carrynomotormen.

My invention resides in a system of control for the trains orcars-involving a block revent collision between cars or trains, anres-ides more particularly in means for automatically accelerating,braking, starting and stopping the trains or cars.

My invention resides also in a system for indicating automatically ineach station the position of cars or trains on the line and forindicating whether a particular apto be stopped at the to pass itwithout stopping; and my invention lecting means used in connection withsuch a system.

My invention resides in other features hereinafter described andclaimed.

For an illustration of one of the forms of my invention reference is hadto the accompanying drawings, in which:

Figure 1 is a diagram of the'connections upon a car and between thecarand the track and conductor rails and one type of controller, whichis shown in the reversing position or position in which it makes suchconnections as will cause the car to start backward.

Fig. 2'is a diagram of the same connections excepting that thecontroller is shown in the braking position or position in which itmakes such connections as will cause the car to be electro-dynamicallybraked. Y

Fig.3 is a diagram of the sameconnecthe controller is shown in thestarting position. or position'in' which it makes such connections aswill causethe carto start forward.

'Fig. 4 is a diagram of the same connections excepting that thecontroller is shown in the through position. or position in which itmakes such connections as will cause the car to continue at apredetermined speed. 1

Specification 0: Letters Patent.

KENNETH E. STUART,

resides in sesection when they made-by the l in the through or normalposition, which in Patented Sept. 25, 1917. application filed May 1,

diagram of the electrical apconnections at a terminal sta- Fig, 5 is aparatus and tion. a

Fig. 6 is a similar diagram (shown for convenience in three parts) forthe first block section, supposed to adjoin the preceding sect'ion onthe right. I

Fig. 7 is a similar diagram for the second block section, supposed toadjoin the preceding section on the right.

Fig. 8 is a similar""diagram for the third block section, which includesan intermediate station and is supposed to adjoin the preceding sectiononthe right. This figure also shows diagrammatically the electricalapparatus and connections at the said inter mediate station. I Figs. 9and 10 are similar diagrams \for portions of the fourth and fifth blocksectionsrespectively, each supposed'to adjoin the preceding section onthe right. Fig. 11 is a diagram of the connections made by thecontactors of the first block'section when they are in the brakingposition or position which causes the train to come to rest upon thissection.

Fig. 12 is a diagram of the connections made by the same contactors whenthey are in the starting position or position to restart the train afterit has been brought to rest upon this section.

Fig. 13 is a made by the same contactors when they are in the throughposition, or normal position, which in this case are such as to re tardthe train to a speed at which it can diagram of the connections safelyenter upon the curved portion of the line. Fig. 14 is a diagram of theconnections made by the contactors of the second block are in thebraking position. l

Figs 15 is a diagram ofthe connections made by the same contactors when,they are in the starting position.

Fig. 16 is a diagram of the connections same cont-actors when they arethis case are such as to accelerate the train again to full speed andthen pass it over the remainder of the section at substantially thatspeed. g

Figs. 17, 18 and 19 are diagrams of the connections made by thecontactors of the third block section when they are in the braking,starting and through positions re-v made within the same controller whenit is in the starting position.

Figs. 22, 23,24 and 25 are diagrams of the connections made within thecontroller for the approach section of either station when it is inthejreversing, braking, through and starting positions respectively.

Figs. 26, 27, 28 and 29 are diagrams of the connections made within thecontroller for the unloading section, loading' section or siding sectionof either station when it is in, the reversing, braking, neutral andstarting positions respectively.

Figs. 30- and 31 are diagrams of the'connections made within thecontroller for the braking section of the intermediate station when itis in the braking and starting positions respectively.

Fig. 32 is a diagram of the connections made. within the controller forthe switch points of the intermediate station when it is in the stationposition, or position in which the switch points are set to direct a carinto the station.

Fig. 33 is a diagram of the connections made within the same controllerwhenr-it is in the past position or position to direct a car past thestation.

Fig. 34 is a side elevation, partly in section on the line 11 of Fig.35, of one of the contactors above. mentioned.

Fig. 35 is a plan view of the same, part being shown with the coverbroken away.

Fig. 36 is an end elevation of the same, the left half being in sectionon the line 22 and the right half on the line 77 of Fig. 37 is asectional end elevation of the same, on the line 8-8 of Fig. 34.

F i 38 is a horizontal section, some parts in p an, on the line 33of'Fig. 39, ofa single ended relay.

Fig. 39 is a plan view of the same.

Fig. 40 is a section on'the line 55 *of Fig. 38.

' Fig. 41 is an end'elevation, partly in sec-v tion, on the line 66 ofFig. 38. U

Figs. 42 and- 43 are side elevations, partly in section, and plan View,respectively, of a modified form of relay.

Fig. 44 is a diagram showing the curves otretardation from full speed torest of an empty car and a loaded car when my system of equalizing thebraking cfi'ect upon the two is employed.

Retei'r ng now to Figs. 1, 2, 3

and 'l, are contact conductor rails for the motor fieldand armaturerespectively. ex-

' tending alongv thetrackway andinsulated.

Fig. 34.

and 4,1, I

from the ground .and from the track rails T T M is the electric motordriving the car through the gears G and G and wheels W,. S, and S arecollector shoes carried by the car and bearing upon the conductor railsT and connections upon the car are from T, through the shunt field F,and'the point 19 to the frame of the car F and thence through the wheelsto and through the track rails T There is also a connection from Tthrough the differential "series field F and the brush.

B,, to the'motor armature A and thence through the brush B point 19, carframe F and wheels to the track T There are thus three connections tothe motor, a. 6., one to the shunt field, one to the armature, and areturnconnection common to both field and armature. These are used tostart, stop and reverse the car in the following manner:

Upon certain sections of the line, which will be clearly indicatedhereinafter, the conduct-or rails T and T,, as well as both the trackrails T are insulated from the similar rails of the troller not upon thecar. Upon such portions of the line the car may therefore be controlledby an operator at a distance. The manner of doing this is illustrated inFigs. 1,2,3and4.

The controller used is merely an adaptation of a well-known commercialtype having fingers bearing upon a common drum which in variouspositions makes various connections between them. In this case there areeight fingers and four positions of the drnm The fingers are numbered 11to 18 inclusivelyand the connections established between them by thedrum in each of its several positions are indicated by the lines joiningthem and passing to the right of them.

adjoining sections of the lineand connected to a manually operated conReferring to Fig. 3, it will be seen that there Isa connection from thepositive main to the finger 12 and thence through the drum to the finger11, which is connected to the conductor rail T,, which, it will beremembcred. has a connection through the collecton shoe S to theshuntfield of the motor M on the ear. The finger 13 has'a connection throughthe rheostat or resistance R, with the positivemain and through the drumto the finger 15, which in turn is connected to the conductor rail Twhence. the connection is through the collector shoc'S to the armatureof'the motor M tl'irough series field winding F. The finger 16 isconnected to the track rails T and also tln-ough the drum to the finger17, which is connected to the negative main. As already explained, boththe armature and shunt field ha ve a return connection to the trackrails T5, connections as shown in Fig. 3. therefore, the motor field\Vith the F will be excited to full T respectively. The electrical 0strength while the armature will receive cur- I rent at a reducedvoltage,

which may be starting the car from field F is in. opposition but thecurrent flow made suitable for rest, and the series to shunt field Fthrough F is not great, due to resistance R and therefore the motorfield is not greatly weakened by F As the car is intended to move atslow speed only while under the control of these controllers, it is notnecessary to provide another position in which the rheostat R is cutout. Under'certain circumstances to be explained later, however,

. it may be desired tokeep the car moving uniformly at the reduced speedwith which it arrives upon the portion of the line in question, and forthis purpose another position of the controller is provided as shown inFig. 4. In this position the connections are the same as beforeexcepting that the finger 15 which supplies the motor armature is nowconnected through the drum to the finger 14 which receives currentthrough a greater resistance than the finger 13.. The connections forbraking the car are shown in Fig. 2. In this case the motor field F, isexcited to full strength as before,

while the armature instead of being con transferred through nected tothe positive main is connected through, the drum and finger 16 to thetrack rails T thus completing a short circuit through the armature. Anyrotation of the armature will now cause it to generate anelectro-motive-force which on account of the low resistance of thearmature circuit will cause aheavy current to flow which in turn resiststhe rotation of the armature, or in other words exerts a braking effecton the This armature current is in reverse direction, and, passingthrough series field F.., causes the latter to act. cumulatively withthe shunt field F to produce a still.

stronger fields As will be shown later, by interposing a suitableresistance in the armature circuit (not shown in Fig. 2) I regulate thebraking effect so as not to damage the motor or cause the car wheels NV,to skid on the rails T The method of reversing the directions of the carisshown in Fig. 1. In this case it will be seen that the motor armatureis con' nected through the drum to the finger 12, which receives thefull voltage from the positive main; The return connection from thetrack rails T, is. however, no longer directly to the negative main butis through the drum and finger 18 to the negative main through therheostat The field connection from the conductor rail T, has also beenthe drum and finger l? to the negative main direct. With theseconnections it will be livid is now connected in serieswith' thearmature, 'hut in shunt or parallel with the rheostat H 'lhus, thecurrent now flows and 18 and the rheostat and is now the same as vfield,making a compound field. Without ened as it, gathers speed.

seen that the shunt from the finger 15 through the conductor rail T thedifferential series field'F and the armature to the point 19, where itdivides, part returning through the fingers 1G R to the negative main,while a part flows through the shunt field and fingers l1 and 17 to thenegative main direct. As the resistance of R is very great compared withthat of the remainder of the armature circuit,,the fall of potentialthrough it at the instant of switching on the current with the motor atrest will be verynearly the full voltage of the power supply. In otherwords the shunt field will receive very nearly the full'voltage of the'mains across its terminals and will be excited to a correspondingdegree. It will be noticed, moreover, that the direction of the currentin the shuntfield has been'reversed, that of the series the latter, themotor would now develop a torque in the reversednrection approximatingits normal..startingtorque... Bymeans of the cumulative field is furtherstrengthened and the torque developed in the reverse. direction can bemade to equal or exceed the normal direction starting torque.

It will be noted thatvthe series turns are not essential to this methodof reversing, but

series starting turns the are useful. .They are likewise'useful in theoperation of braking, since in this case the current 111 the armature isreversed and the series turns are cumulative with the shunt turns, asabove described. It may also be mentioned that the diflerential seriesturns improve the constant speed characteristic of the m0tor'in normalahead running and if properly proportioned are therefore an advantagefrom every point of view. As the motor gathers speed when so reversedthe current and consequently the fall of poten' tial through therheostat R, will diminish. This will weaken the shunt field exactly asthe field of a series wound motoris weak- A shuntmotor reversed in thisway therefore develops series motor characteristics. But as I use thismethod of reversing only for side tracking and switching within thestations where the car is under control of the operator, this feature isnot objectionable. This method of reversing avoids the use ofan extracontact conductor rail, which would otherwise be necessary to provide aseparate returncon'nection from the shunt field for reversing thecurrent through it.

lfhe manual control of the car above described, a". 6., by means ofcontrollers, is used only in or near the stations. At other points themovement of the car is independent of the operators, but subject to theautomatic control of a block system.

Referring to Figs. 5,- 6, 7, 8, 9 and 10, T

' conductor railand T ductor rails into the sections above refer n redto.

At the approach to each station it will obviously be necessary toprovide means for bringing the car to rest. In Fig. 5 the 1nethod ofaccomplishing this at a terminal is shown. This is accomplished bydisconnecting the armature conductor rail T from the source of currentS0 (connected to positive main pm and to negative main mn) andconnecting it to the track rail T through a resistance while the fieldwinding F is, separately excited at full strength, as already described.The minimum safe resistance in the armature circuit 'is determined bythe speed of the car, and as the'car is retarded the resistance cantherefore be out out step by step. In Fig. 5, the sections of thearmature conductor rail I -I I I,, I,I

I I are each connected to the track rail T through successively smallerportions of the resistance or rheostat R The section 'I -I is connectedto the positive mainpm,

for reasons that will be explained later. The sections of'the armaturecontact conductor rail T such as I I etc., which are for brakingnormally connected to the track rails T, I call retarding sections. Thesection I,I vI call an equalizer section. The whole series collectivelyI call a'braking section. v

The field conductor rail T throughout the retarding sections, as Well aselsewhere, is likewise divided into sections (as at I I I etc, Fig. 5.)which haveto do with the system of indicating in the stations theposition of. the cars in transit and also with the block system, both ofwhich will be described later. Each section of the field conductor railreceives currentthrough a. series solenoid in the relays R R etc. Theseseries solenoids are of negligible resistance so that the fieldconductor rail may, except in the ease of" sections that are under thecontrol of controllers, be considered to be in permanent connection withthe positive main pm, causing the motor field F to be excited as stated.

The operation of the retarding sections willibe better understood byreference to Fig. 44. In this figure, the full line 1 is the curve ofretardation of a loaded car from 30 miles per hour to rest, ordinatesbeing proportional to speed and abscissae to distances. In the caseillustrated, on the first retarding section, 2'. 0., I,I.,, the speed isretarded from 30 to 15 miles per hour. Upon the equalizing section I Ithe motor on the car receives current from the source of power tendingto drive it, but the resistance interposed between it and said source isso.

motor armature whose loaded car,

calculated that the torque developed by the motor is 'insufficient toovercome the resist ance of the car to forward motion, which thereforecontinues to be retarded, though at a reduced rate. The car is retardedon the equalizing section from 15 to 10 miles per hour. On the remainingretarding sections, the speed is reduced from 10 to 5 miles per hour,from 5 to 2% miles per hour and from 2;; miles per hour to restrespectively.

In Fig. 44 the dotted line e 0 is the curve of retardation of an emptycar arriving at the same speed as the loaded car.

The function of the equalizing section is as follows:

The braking effect of a short-circuited field is separately. excited atconstant strength is, with a given resistance in the armature, circuit,propor-' tional to the speed. In other words, for a given speed it isthe same for both the loaded and empty cars. But at a given speed theempty car possesses less energy than the loaded car, consequently itwill be retarded more rapidly. In the case illustrated in Fig. 44 theempty car reaches the equalizing section with a speed of 13% milesperhour, as compared with 15 for the loaded car. At this reduced speed, however, the empty car receives agreater current from the source of powerthan did the and gains in speed relatively to it. It leaves theequalizing section with-a speed of 11 miles per hour as compared with 10for the. loaded car. From this point it begins again to be retarded morerapidly than the loaded car and finally comes to rest at the same spot(20, Fig. 44).

With any system of braking depending upon friction there is not only agreat Varia tion in the distance required to bring a train to rest onaccount of variation in the coefficient of friction, but there is also agreat difference between empty and loaded cars (100% or more); Withdynamo-electric braking this variation is reduced to about l2-;;%. Bymeans of the equalizing section, however, it can be further reduced to anegligible quantity.

It will be observed that on each of the retarding sections the speed isreduced in' the same ratio (being halved in this case, except that onlast section the speed is reduced-to zero). The object of this is asfollows? The maximum allowable electro-dynamic braking effect, expressedas a torque in foot pounds, at the beginning of each section is limitedeither by the adhesion of the driving 'wheels or by the capacity of themotor, and

- at its end 'a braking effect which bears preceding section andsection, etc.

tion is secured by so proportioning the-- lengths of the sections andtheir associated armature circuit resistances that the braking effectsat the initial ends of the sections are substantially equal, and the'braking effects at the terminations of the sections are likewisesubstantially equal, it being remembered that the speed nevertheless isalways decreasing; and furthermore, the ratio of the braking effect atthe beginning of each section to the braking effect at the terminationof each section is substantially the same r'or all sections with theexception of the last, in'which case the same maximum braking eifect isproduced at the initial end of the last section, but the braking effectis reduced to zero as the car comes to rest. For instance, at the pointat which it is desired that the motor braking should begin theresistance to be insertedin the armature circuit in order to give themaximum allowable braking torque is determined. With this factor knownthe rate of negative accelera tion or braking is determined. From thisthelength of the section necessary to insure the desired ratio to thebraking effect at its initial end is determined. The next step is thedetermination of the resistance to be 1nserted in the armature circuitfor the next succeeding braking section.

This, however, is a function of the speedat the end of the is thereforedetermined in the same way as the corresponding resistance for the firstsection. This process is followed out for the desired number ofsections, and we have the following relation:

in which T is the braking elfect or at the initial end of the firstsection, T the effectat the end of the first section. T, the effect atthe beginning of the second section, and T, the effect at the end of thesecond It being remembered, however, that the braking effort isproportional to the speed and. that the speed at the end of the firstsection is substantially equal to the speed at the beginning ofthesecond section,

torque and so on, we may write:

are the speeds at the beginning of the successive retarding sections. Ifthis law is followed it will be found that the successive retardingsections become shorter and shorter as in Fig. 44.

The retarding sections are normally at the entrance tothe station, theirfunction being to prevent thecars from entering the station eircept atthe volition of the operator. When the "cars have come to rest or beenretarded to a safe speerh'therefore, it is the positive main pm.

call the approach section is under the control of the controllernecessary that the operator should be able to cause them to enter thestation.

This is accomplished by connecting the retarding sections to acontroller in the station by means of which the operator may-by amovement of a lever disconnect them simultaneously from the track railand connect them to the source of power.

In Fig. 5 this controller isshown at O It will be observed that theretarding section L L' is permanently connected throu h. the rheostat Rto the track rail and the equalizing section 1 l, ispermanently-connected through the rheostat R, to The operator thus hasno control over the car until it'has been retarded to a safe speed. Theremaining retarding sections are,however, the fingers 22, 23 and 24 ofthe controller C,, and in the position shown in Fig. 5, these fingersare connected through the drum tothe fingers 25, 26 and 27. Thence 25 isconnected directly to the and 27 are connected to the track rail through5 the rheostat R as previously stated. The connections made by the drumof this controller in this (the braking) position are shown again forclearness in Fig. 20, side by side with the connections'made by it inthe alternative or starting position (Fig. 21). From this figure it willbe seen that in the starting position the fingers 22, 23 and 24 areconnected to the finger 2i, and from Fig. 5 it will be seen that thefinger 21 is connected through the rheostat R, to the positive main. Inthis case there are no reversing or through positions of the controller.The functions of the finger 28 and the solenoid 29 will be explainedlater.

The braking section ends at I and at this point another section of thetrack, which I section, begins. This 0,, which is similar to thecontroller that has already been descr bed in connection with Figs. 1,2, 3 and 4. It will be remembered thatit has four positions, viz.,revet-sing, braking, starting and through. For clcarness. the drumconnections in each of these positions are shown again in Figs. 22, 23,2t and 25. The object of the through position may now be understood. Itis that this approach section I,-I, may serve as an equalizer sectionfor trains that have been admitted from the braking section, theoperation being the same as that of the equalizing section alreadydescribed. By this means ,an empty section at a speed less than desiredspeed because it has been to greater degree braked on the precedingbraking section, will be ad celerated because the current required forthe acceleration is relatively smaller and occasions smaller drop ofpotential in the resistance R with thev result that there is connectedto track rail and 26 car. arriving on this tively higher voltage than inthe case of a loaded car arriving under similar conditions.

The approach section in general enters the station and is used forshunting or switching the cars, hence the reversing, braking andstarting positions.

From the approach section the car normally passes overaswitch pointorsystem of switch points which may direct it on to an unloading sectionor ,upon a siding, at the will of the operator. In Fig. 5, the unloadingsection is from I, to I, and a sidin is shown from L to I I, to I, is aloading section.

These three sections in the order last" named are under the control ofthe controllers C C, and C, respectively. The controllers are allsimilar to each other, but differ from the controller C in that theyhave no through position, the place of which is taken by a neutralposition, in which all connections to the section are interrupted.

The drum connections for the several posi tions of these controllers areshown in Figs. 26, 27, 28 and 29. They are similar to those of C exceptthat instead of the two fingers 13 and 14 connected through differentresistances to. the positive main 12m, there is but one, indicated at33.

It will be noticed that the several controllersare not associated withthe same rheostatsR- R,, R, and R either for receiving current throughthem from the source, or for braking purposes. The object in this is toavoid the use of the same rheostats for two sections upon which it maybedesired to move trains at the same time, for

if two trains were to take current simultaneously through the samerheostat the current and consequently the fall of potential same as whenonly one was taking current and neither train could develop the requiredstarting torque.

It will be noted thatthe field conductor rail T and the track rails T,of each of these sections under control of controllers having areversing position are insulated from the adjoining sections as well asthe armature conductor rail (as atl and I, F ig. 5). This is necessary,as in reversing, the field conductor rail completely changes in itspolaritv, while a considerable difference of potential is createdbetween the section of the track rail and adjoining sections owing toits being connected to the negatire main am. through a. resistance aspreviouslyexplained.

It is to be understood that the arrangev ment oi an actual station maybe. more or less of a modification of the arrangementdescribed whileconformingto it in that there will be one or more sections completelyinsulated from adjoining sections and each unthrough the rheostat wouldnot be the der the control. of a separate controller, whereby cars canbe moved on one section without disturbing those on another.

W hen a car passes over the insulators I, or I it leaves the control ofthe operator at the station and enters upon a series of sectic-n5 9 11l27 I12 I137. 1a 14 and I14 1 which I call accelerating sections. Theaccelerating sections are normally connected to the positive mainthrough successively less portions of the rheostat R The field conductorrail is likewise sub-divided, but as a1- rcady explained, all of itssections, except in the case of sections that are under the 'control ofcontrollers, are permanently connected to the positive main pm.

As the car advances over the accelerating sections, therefore,theresistance that was interposed in the armature circuit at start ingis cut out step by step until at I the armature is receiving fullvoltage, the field F, being meanwhile separately excited to fullstrength, causing the car to be accelerated to full speed.

The section I,I -I is connected to the positive main through thecontactor K,, which has to do with the block system to be explainedlater.' With this exception, the connections of the acceleratingsections of the terminal station shown in .Fig. 5, with the positivemain are permanent. i

tive-force), s the speed at any instant, T

the motor torque and R the total resistance of the armature circuit,then with the field separately excited to full strength:

'1 const.

The maximum positive accelerating torque,generally expressed in footpounds, at the beginning of each section is limited either by theadhesion of the driving wheels or by the capacity of the motor, and iscon sequently the same for all of the sections. To procure suitable meanaccelerating effect with a given number of sections, I prefer to makethe mean accelerating effect upon each "of them the same. This conditionis secured by so proportioning the lengths of the sections and theirassociated armature" circuit resistances that the accelerating effectsat the initial ends of the sections are substantially equal and theaccelerating effects at the terminations of the sections are senlike-wise substantially equal; and further- 'more, theratio:ofaccelerating eilect at the beginning of each section totheaccelerab. ing efiect at the termination of each section issubstantially the same for all sections with the exception of=the last,in which case 'the same maximum accelerating effect is produced at theinitial end of the last section, but the accelerating toaero as'thecarnttains full speed. For instance; at the starting point of the car ortrain the resistance to armature circuit in order to givethe maxi mumallowable accelerating torque is determined. With this factor known thera-te of acceleration is determined. Fro-mthis the speed an the desiredratio to .at its initial end is determined. T e next beginning of thesecond torqueat theend of=the second section, etc. 1 a Suhstituting-forveach torque value in the control-of the controllers C- length ofthe section necessary to'insure at its end an accelerating effect. whichbears the aecelera-tin effect.

step is the determinationzof the resistance to be inserted inth'e"however, is a function of the speed at the end of the preceding-sectionand .is there fore detemnined in the same way as thecorresponding-resistance for the first section. This process isfollowedoutfor the desired number of sections, and we have the followingrelation:

. E T; in which T isthe accelerating torque at the start, T the;torqueat'the endof the first accelerating section, T the torque at thesection;: and T, the

etc.,

last equation its equivalentfas given. by a precedin equation as arelationbetween resistance,- we have the following in which 8 s etci,are the speeds at the beginning of'thewsuccessive accelerating sections.This equation therefore expresses a condition of the onost efiectiveacceleration witha given ammber ofsections.

At the intermediate station, proach, unloadingiand-siding sections (I 31and sa 33) 1' 11nd or n and C10 are found, but otherwise thisrcspectivel station diers matter-i lly fromthe terminal station just'described-in'ways that can best be explained in--connection with theblock system.

-' It has already been stated that the held conductor 'railisdividedf'into sections, each of which receives current through a seriescarried along the line from one end to the effect is reducedbec'inserted in the I armature circuit for the next succeedingacceleratmg section. This,

type justdescribed.

( isp 212* For this pure other and is everywhere indicatedby the sign(Figs. 5 10 inclusive).

The construction of these relays will be understood by reference toFigs. 38-43 inclusive.

. The relay, as R is horizontal.

C is an iron core passingthrough the solenoids S iatrid S of which theformer is the low resistanceseries solenoid through which thesectionsoi' the field conductor rail are supplied. When S is energizedit drawsthe core C in thedirection of the arrow. in Fig. 38. 7 W, arecontacts between which passes the sleeve S which is mounted upon thebrassrod S, forming a continuation of the core C The sleeve S, ismetallic and in-one pos'tion makes contact between the contacts W At theend which comes between these two contacts-when the core is to the left,however, the 'sleey. S is surfaced with an insulating material-fill).and in this position the connection between the two contacts isinterrupted. 'The' sleeve S, is made free. to slide upon the rod' S, inorder that it may lag back during the first half of themotion of thecore C 1,, in the opposite direction to the arrow in Fig. 38 and com-"press the spring S which during the remainder 'of;lthe grhovementreexpands and quickens thelbrelalting of the circuit. R 3 mm! R Fig. 5,are relays of the Being represented dia-' grammatically, the contactsare shown between the solenoids instead of at one end, but this does notchangethe principle of operation. I hen the solenoid nearest thecontacts' is energized, the connection between the contacts must beconsidered to be established. Relays of this type will bereferred tohereinafter as single-ended relays. R R R etc., Fig. 6, are "relaysexactly similar to those .ju'stdescribed except that thecontactmechanism W N at the one end is duplicated at the other end wherethe stationary contacts are W W Relays of this type will, referred to asdoubleended relays, and'the contacts 1W as interrupting contacts. Figs.42 and 43 illustrate a modified form of relayg' as li inarranged withits axis tended to be operated withits axis vertical so that the weightof the core Qi', and lead weight. 101' in fallingfrom posit onshownbreak the contact, thus shunt solenoid S u Relays of this type willbe called gravity relays. R Fig 5, and R Fig. 8 are of this type. Thesetwo rej lays are likewise shown diagrammatically and notwithstanding 'beunderstood that when the solenoid s energized, connection is establishedbetween the upper contacts; and in thecase of relay R and those like it,the lower contacts are conncoted when the solenoid is deenergized. 1Referring again to, Fig, 5 and taking the their position must dispensihgwith the

